Bearing component having a metallic base body and an alloy-steel coating

ABSTRACT

A bearing component such as a bearing ring includes a metallic base body and at least one alloy steel coating on the base body, the coating being applied to the base body by deposition welding. The base body is preferably non-alloy steel or cast iron, and the alloy includes at least one carbide-forming transition metal such as niobium, tantalum, zirconium, titanium, hafnium, tungsten, molybdenum, vanadium, or manganese. The coating can form a raceway of the bearing component or a structural element such as a flange. Also a method of forming such a bearing component is provided.

CROSS-REFERENCE

This application claims priority to German patent application no. 102018 220 315.6 filed on Nov. 27, 2018, the contents of which are fullyincorporated herein by reference.

TECHNOLOGICAL FIELD

The present disclosure is directed to a bearing component including ametallic base body and a coating including alloy steel.

BACKGROUND

The present disclosure is directed to a bearing component having a basebody that forms the bearing component and at least one coating appliedonto the base body.

A bearing component is known from the prior art, for example, arolling-element bearing ring that has at least one raceway for rollingelements. Here the raceway should in principle have certain mechanicalproperties, in particular a high hardness, so that damage due torolling-element fatigue, wear, forced rupture, or creep, etc. can bereliably avoided in a suitable manner for a period of time that is aslong as possible. For this purpose it is known to coat the raceway witha coating in order to harden its surface, and, possibly, to betterprotect against corrosion. Here and in the following the term “surface”is used such that the surface-adjacent zone (edge layer) is comprisedtherein.

It is furthermore known from the prior art to harden the surface of acomponent comprised of steel in order to obtain a suitably hard surfacefor a specific application. For example, case hardening, carbonitriding,and inductive hardening are known. However, the surface hardness canonly be influenced to a limited extent, thermally or thermally andchemically, by this method. In addition, such components can haveproperties that are undesirable at least for certain applications; forexample, they may have a comparatively high brittleness of the edgelayer, which can lead to the risk of crack formation.

SUMMARY

It is therefore an aspect of the present disclosure to provide a bearingcomponent that, with the possibility of cost-effective manufacturing, isdistinguished by advantageous surface properties.

In the following a bearing component is provided that includes a basebody (substrate, core) manufactured from a metallic material, which basebody forms the bearing component, and that includes at least one coating(plating, cladding, deposition layer) applied (attached, clad, fused,deposited) onto the base body. The bearing component can be, forexample, an inner ring or outer ring of a rotating rolling-elementbearing, a raceway of a linear bearing or of a plain bearing, a flange,a cage, a seal, or a rolling element. The bearing component can be newlymanufactured according to the disclosure, or remanufactured (in thelatter case optionally with improved performance) for further use (aftera certain operating period), for example, after a thorough cleaning andmechanically ablating functional-surface preparation.

The base body can be manufactured from a cost-effective metal.

According to one preferred embodiment, the base body is made ofnon-alloyed steel, for example, non-alloyed structural steel (e.g.,S185, S235, S275, S295, S355; different variants/material numbers arerespectively possible: e.g. S275JR/1.0044, S275JO/1.0143) or non-alloyheat treatable steel (e.g., C22/1.1151, C35/1.1181, C40/1.1186,C45/1.1191, C50/1.1206), or from cast iron (e.g. nodular iron, GJS, oraustenitic-ferritic or ausferritic cast iron with spheroidal graphite orwith carbides, ADI or CADI, also austempered or bainitic cast iron); thelatter materials are relatively cost-effective. However, the base bodycan also be manufactured from a different metallic material, forexample, a through, case or induction hardenable, stainless orheat-resistant rolling-element-bearing steel such as the standardrolling-element-bearing steel 100Cr6 (material number (EN): 1.3505) orcarburized or non-carburized case hardening bearing steel 18NiCrMo14-6(material number (EN): 1.3533), a low-alloyed heat treatable steel, suchas 42CrMo4 (material number (EN): 1.7225) or a different metallic alloy,such as, for example, from an aluminum, copper, or titanium material.The selection of the material allows, for example, a setting(modification) of the properties of the base body (e.g., quenching andtempering of a low-alloyed heat treatable steel), which properties arefavorably adapted to the requirements of the particular application ofthe present disclosure. S235 has a composition (in wt. %) of C: ≤0.22,Mn: ≤1.60, P: ≤0.05, S: ≤0.05, Si: ≤0.05, N: ≤0.009, the remainder beingiron and unavoidable impurities. S355 has a composition (in wt. %) of C:≤0.23, Mn: ≤1.60, P: ≤0.05, S: ≤0.05, Si: ≤0.05, N: ≤0.009, theremainder being iron and unavoidable impurities. C22/1.1151 has acomposition (in wt. %) of C: 0.17-0.24, Si: ≤0.4, Mn: 0.4-0.7, Ni: ≤0.4,P: ≤0.03, S: ≤0.035, Cr: ≤0.4, Mo: ≤0.1, the remainder being iron andunavoidable impurities. C35/1.1181 has a composition (in wt. %) of C:0.32-0.39, Si: ≤0.4, Mn: 0.5-0.8, Ni: ≤0.4, P: ≤0.03, S: ≤0.035, Cr:≤0.4, Mo: ≤0.1, the remainder being iron and unavoidable impurities.Thus, the base body may generally have a composition (in wt. %) of C:≤0.4, Mn: ≤1.60, Ni: ≤0.4, P: ≤0.05, S: ≤0.05, Si: ≤0.4, Cr: ≤0.4, Mo:≤0.1, N: ≤0.009, the remainder being iron and unavoidable impurities.

In general, non-alloyed steel or cast iron or also aluminum, copper, ortitanium alloys are not suitable for manufacturing a bearing componentbecause these materials do not have the required surface properties(e.g., hardness, fatigue life, wear resistance). However, since bearingcomponents according to the present application have a coating thatprovides a more robust surface having greater, more suitable hardnessand strength, the materials mentioned above can be used for forming thebase body according to the present teachings.

In particular a comparatively less-hard material can thus be used forthe base body in applications in which a non-throughgoing mechanicalload (e.g., rolling) is expected to stress the interior regions lessstrongly than the surface (edge layer), e.g., in a bearing ring or arolling element of a bearing.

In order to achieve a high hardness for the surface of the coating, thecoating is composed of an alloy steel and is applied onto the base bodyby deposition welding (also known as cladding). The coating is thussuitable, for example, for forming the raceway surfaces of a rotating orlinear rolling-element bearing or of the raceways of a plain bearing.

Furthermore, deposition welding has the advantage that an alloyformation can be effected “in situ” in the liquid phase during thewelding process or in the coating applied onto the base body. In thisway the possibility arises, for example, to also “directly” add, to thesteel applied as coating, such chemical elements whose admixture wouldbe technologically difficult in conventional melt-metallurgy (volume-)manufacturing processes.

According to one preferred exemplary embodiment the alloy steel of thecoating includes an alloy made of a base steel and at least onecarbide-forming transition metal. By using the carbide-formingtransition metal, the coating can be made to include (form) (special)carbides, carbonitrides, and/or nitrides; here the deposition weldingcan ensure that the carbides, carbonitrides, and/or nitrides arecontained in the coating in a particularly high proportion. Usingconventional methods, corresponding proportions cannot be achieved orcan only be achieved with great technical effort.

The carbides, carbonitrides, or nitrides are present in the alloy of thecoating in particular in the form of small particles that are uniformlydistributed with high density. The particles can be formed in particularby a deformation-induced dynamic precipitation reaction, after thedeposition welding process, with a subsequent reshaping treatment (e.g.,rolling, pressing, forging) at an elevated temperature (relative to roomtemperature), with (e.g., thermomechanical treatment) or withouttemporal controlling or regulating of the temperature, and a suitablyadjusted degree of deformation of the coating. Here a desirably smallparticle size of less than 1 μm can be achieved due to thedeformation-induced precipitation of dislocation cores from (high)supersaturation of the dissolved transition metal atoms (precipitationpotential) in the solid solution.

Alternatively the particles in the coating can also be (purely)thermally (e.g., isothermally, in a plurality of temperature stages, ortemperature-controlled as desired) precipitated by a heat treatmentsubsequent to the deposition welding.

Reshaping and heat treatment can also be carried out in any combinationfor precipitation of the particles.

Furthermore, for example, initially, a solution annealing can beeffected at a high temperature (e.g., over 1100 or 1200° C.) in orderto, for example, dissolve in the matrix the larger particles formedduring the solidification for the later precipitation of the desiredsmall particles. It can thus be achieved that the particles arecomparatively small and their number is comparatively large, so thatsubsequently the particles overall—with a given total volume ofparticles—have a particularly large surface area. In addition to theadditional strength increase associated therewith (small particledistance, principle of precipitation or dispersion hardening), this isin particular thus of significance since the carbide, carbonitride, ornitride particles function as microstructurally irreversible adhesionsites for strong internal binding of hydrogen, which is harmful to thematerial properties of the steel and diffusing in the lattice. Ingeneral, hydrogen can become incorporated in a metallic microstructure,wherein in particular the mobile (diffusible) and weakly (e.g., atdislocations) bound hydrogen impairs the mechanical behavior and, forexample, reduces the toughness; in steels, it is known as hydrogenembrittlement. As a consequence thereof, there is a risk of ahydrogen-induced crack formation, and accelerated material fatigue canresult. The risk of a hydrogen-induced crack formation (hydrogen-inducedcracking, HIC) and a hydrogen-induced material fatigue can be reduced inparticular by embedding the above-mentioned particles in the alloy ofthe coating.

In principle the greater the particle density, the better. However, inorder to avoid negative effects on the material properties the volumeproportion of the particles should not exceed approximately 10%.

According to one preferred exemplary embodiment the at least onetransition metal is niobium, tantalum, zirconium, titanium, hafnium,tungsten, molybdenum, vanadium, and/or manganese. Here the choice of thecarbide-forming transition metal(s) serving as the alloying element(s)hardly influences the trapping or absorption capacity of the resultingprecipitation particles for hydrogen, but significantly influences thetechnological manufacturability, the design, and properties of thetarget structure in the steel of the coating. To reduce theabove-mentioned effect of the binding of hydrogen atoms (as well as toincrease strength), it is particularly advantageous to form particlesthat are as small as possible and are as evenly distributed as possible.Niobium, tantalum, and zirconium are therefore particularly preferred asthe carbide-forming transition metal(s), since these elements, owing toa relatively high precipitation potential, i.e., high speed ofnucleation (often referred to as nucleation rate), fordeformation-induced precipitation of carbides, carbonitrides, and/ornitrides, and simultaneously owing to relatively slow precipitationkinetics, lead to denser precipitation particles being finelydistributed in the structure during a reshaping (forming) at an elevatedtemperature, compared to titanium and vanadium, which are less suitablein this respect. This desired precipitation behavior during thereshaping process at an elevated temperature can be demonstratedqualitatively in that numerous grains, which are uniformly distributedat the dislocations in the microstructure, form quickly (high nucleationspeed), but then subsequently grow only slightly (low grain growthspeed).

Zirconium has the further advantage of tending to precipitate smallincoherent particles that are particularly favorable for hydrogenadhesion (“trapping”), as well as for increasing strength, and inaddition also scarcely coarsen due to the slow diffusion of zirconium inthe steel matrix in the event of an optional subsequent heat treatment(e.g. martensitic or bainitic hardening of the coating).

According to one preferred exemplary embodiment the mass proportion ofthe carbide-forming transition metal in the alloy is between 0.01% and5%, particularly preferably between 1% and 3%, since in this way—incomparison to conventional bearing components—a particularly highproportion of the transition metal can be achieved, which can beintroduced into the alloy during the in situ welding process.

According to one preferred exemplary embodiment, the base steel of thealloy is an overrolling-resistant steel, in particular athrough-hardening rolling-element-bearing steel, for example, 100Cr6 ora derivative thereof, such as, for example, 100CrMnSi6-4 (materialnumber (EN): 1.3520), 100CrMo7-3 (EN 1.3536) or 100CrMnMoSi8-4-6 (EN1.3539). These steel grades are characterized by high hardness(typically between 58 and 65 HRC, depending on the heat treatment, overthe entire cross-section or in the edge layer), high rolling contactfatigue resistance, and good wear resistance, such as is known as suchfor rolling-element bearings. 100Cr6 has a composition (in wt. %) of C:0.93-1.05, Si: 0.15-0.35, Mn: 0.25-0.45, P: ≤0.025, S: ≤0.015, Cr:1.35-160, Al: ≤0.050, Cu: ≤0.30, the remainder being iron andunavoidable impurities. 100CrMnSi6-4 has a composition (in wt. %) of C:0.93-1.05, Si: 0.45-0.75, Mn: 1.0-1.20, P: ≤0.025, S: ≤0.015, Cr:1.40-1.65, Al: ≤0.050, Cu: ≤0.30, the remainder being iron andunavoidable impurities. 100CrMo7-3 has a composition (in wt. %) of C:0.93-1.05, Si: 0.25-0.35, Mn: 0.60-0.80, P: ≤0.025, S: ≤0.015, Cr:1.65-1.95, Mo: 0.20-0.35, Al: ≤0.050, Cu: ≤0.30, the remainder beingiron and unavoidable impurities. 100CrMnMoSi8-4-6 has a composition (inwt. %) of C: 0.93-1.05, Si: 0.40-0.60, Mn: 0.80-1.10, P: ≤0.025, S:≤0.015, Cr: 1.80-2.05, Mo: 0.50-0.60, Al: ≤0.050, Cu: ≤0.30, theremainder being iron and unavoidable impurities. Thus, the coating(cladding) may have a composition (in wt. %) of C: 0.93-1.05, Si:0.15-0.75, Mn: 0.25-1.20, P: ≤0.025, S: ≤0.015, Cr: 1.35-2.05, Mo:≤0.060, Al: ≤0.050, Cu: ≤0.30, and a total of 0.5-5 (wt. %), morepreferably 1-3 (wt. %), of one or more of Nb, Ta, and/or Zr, theremainder being iron and unavoidable impurities.

If the base body is manufactured from a rolling-element-bearing steelsuch as, for example, the standard rolling-element bearing steel 100Cr6,the base steel of the alloy can advantageously be, for example, ahigher-grade (e.g., fatigue-resistant) rolling-element bearing steel,for example, 100CrMo7-3.

According to a further preferred exemplary embodiment, the alloy of thecoating (cladding) is composed of rolling-element-bearing steel 100Cr6as the base steel, and between 1.5 and 2.5 wt. % zirconium, preferably1.8-2.2 wt. % zirconium, more preferably 2 wt. % zirconium, as thetransition metal, or between 0.5 and 1.5 wt. % niobium, preferably0.8-1.2 wt. % niobium, more preferably 1 wt. % niobium, as thetransition metal, or between 2.5 and 3.5 wt. % tantalum, preferably2.8-3.2 wt. % tantalum, more preferably 3 wt. % tantalum, as thetransition metal. Due to their ability to form carbide, carbonitride, ornitride particles that are precipitable in a deformation-induced mannerin a fine distribution according to the methods described herein, thesethree mentioned alloys are particularly well suited as the racewaymaterial of an inner or outer bearing ring.

According to a further exemplary embodiment, a preferred composition ofthe base steel of the coating comprises, in weight percent:

0.25 to 1.3 carbon,

0.1 to 1.0 silicon,

0.1 to 1.5 manganese,

0.5 to 2.5 chromium,

and optionally one or more of the following elements:

0 to 1.0 molybdenum,

0 to 4.0 nickel,

0 to 0.5 copper,

0 to 0.1 aluminum,

0 to 0.1 calcium,

0 to 0.1 vanadium,

0 to 0.1 titanium,

0 to 0.1 niobium,

0 to 0.1 tantalum,

0 to 0.1 tungsten,

0 to 0.1 cobalt,

0 to 0.1 nitrogen,

0 to 0.1 oxygen,

0 to 0.1 boron,

0 to 0.05 phosphorus,

0 to 0.05 sulfur, and

0 to 0.05 tin

the remainder being iron and unavoidable contaminants (impurities), suchas, for example, arsenic, lead, antimony, magnesium.

The mass proportions are indicated herein in weight percent (wt. %) inthe technically-common way. Mass percent is also used with the samemeaning.

According to one exemplary embodiment a bearing component is provided inthe form of a bearing ring, for example, an inner ring of a cylindricalroller bearing, wherein the coating forms a raceway for rolling elementsto roll on. A long service life for the bearing ring can be achievedaccording to such an embodiment.

According to one exemplary embodiment the coating also forms astructure, for example, in the form of a guide flange or retainingflange, or a contour of the raceway. Such a structure can bemanufactured in a particularly suitable manner by deposition welding.

According to one exemplary embodiment the base body is manufactured inits final form (completely dimensioned) prior to application of thecoating/cladding. In such an embodiment, the base body (core) alreadyhas its final shape for the raceway, etc. The coating can then beapplied onto one or more regions of the base body, such as one theregion(s) that will form the raceway(s) for the bearing.

According to a further aspect of the disclosure a method is provided formanufacturing a bearing component, including the following steps: a)providing a metallic base body and b) applying at least one metalliccoating onto the base body by deposition welding, wherein the coatingincludes an alloy steel at least one carbide-forming transition metal.

The deposition welding thus serves here as a method of additivemanufacturing (additive welding), and may optionally also be used forreprocessing (refinishing, refurbishing, remanufacturing), for example,of a used large bearing ring. Since the coating is applied onto the basebody by deposition welding, the alloy can be formed “in situ” during thewelding (cladding) process. Thus in a single manufacturing step, thealloy of the coating can be formed and applied onto the base body.

Here the base body is preferably manufactured from non-alloy steel orcast iron or an aluminum, titanium, or copper alloy. In someembodiments, the base body is formed from non-alloy steel or cast iron.

For example, a plasma arc welding (plasma arc cladding), a laser (beam)welding (laser cladding), or an electron beam welding (electron beamcladding) can be used for the deposition welding.

According to one preferred exemplary embodiment, the alloy steel of thecoating includes an alloy made of a base steel and at least onecarbide-forming transition metal. In particular for forming the coating,the components of the alloy that comprise the base steel and the atleast one transition metal may be first mixed in order to form adeposition material (filler material) that is then applied to the basebody to form the coating by the above-mentioned deposition welding(cladding) process.

Here the component(s) of the transition metal(s) can be provided in pureform, a mixture, an alloy, and/or a chemical compound, for example, anintermetallic phase (e.g., with iron or at least one further transitionmetal), having a comparatively low melting point.

According to one exemplary embodiment, the mixing of the components ofthe coating material can be effected before the deposition welding orduring the process of the deposition welding. Mixing during the weldingprocess is particularly advantageous since in this way a separate mixingprocess can be omitted. A corresponding nozzle assembly, for example,can be used for the mixing.

The components are preferably provided in the form of a powder and/or ofa wire and/or of a band. Particularly preferably powders can be usedthat are commonly available for the widest variety of materials. Themixing for forming the alloy is thereby particularly simple, inparticular when it is effected during the welding. The component thatforms the base steel of the coating can thus be, for example, a powdermade of 100Cr6. The component that forms the zirconium can in particularbe highly pure zirconium powder.

During the application of the coating according to one preferredexemplary embodiment, an alloy of the base steel is formed with thetransition metal that has dissolved as a liquid in the melt or as solidin the substitutional solid solution (e.g., of the austenite). During areshaping treatment (e.g., pressing and/or rolling) at an elevatedtemperature, carbides, carbonitrides and/or nitrides of the transitionmetal are subsequently generated by deformation-induced dynamicprecipitation. Here this thermally-mechanically controlled structureformation is effected in combination with at least one hot, warm, orlukewarm reshaping of the workpiece, wherein the increased temperatureduring the reshaping can be set by a single (common method) or multipleheating, or in a temperature controlled manner by a controlled orregulated heating. In this way the particles can be formed in a suitablyhigh number and with a uniform distribution in the coating.

Here due to such a reshaping not only can the desired particles begenerated in a suitable amount, size, and density in the coating, but inparticular a property optimization can also be effected, for example inthe form of a grain refining for increasing the strength. A closing ofpores or cavities that might possibly be present in the coating afterthe deposition welding can also thus be achieved, for example.

The above-mentioned reshaping processes are each carried out at constanttemperature or at varying, preferably decreasing temperatures (e.g.,after heating) between approximately 1400° C., preferably 1250° C., and500° C. In order to achieve a particularly efficient deformation-induceddynamic precipitation of the particles, the reshaping (e.g., ringrolling) can be carried out at an elevated temperature over a longertime, in particular longer than with usual hot/warm/lukewarm reshaping,for example, over one or more minutes. Here, for example, in a two-stagereshaping process the duration of the first (hot) reshaping at elevatedtemperatures between approximately 1250 and 950° C. (e.g., ring rollingin the range of approximately 1100° C.) can fall significantly below theduration of the second (warm) reshaping (e.g., again ring rolling)between 900 and 600° C. Furthermore, at least one heat treatment(thermomechanical treatment) can be upstream from, between, ordownstream from the at least one reshaping process, wherein furthermorepreferably in the or in each reshaping process or after the lastreshaping process a controlled cooling, for example, a quenching, occursin order to further increase the hardness of the coating.

As mentioned above, it is advantageous if the corresponding particlesare present in the coating in the largest possible number with a uniformdistribution, and have a smallest possible size. During depositionwelding of the described alloy and subsequent reshaping treatment atelevated temperature, carbides, carbonitrides or nitrides are formedthat are smaller than 1 um or smaller than 0.5 μm, or even smaller than0.1 μm or smaller than 0.05 μm.

In addition, by using the methods described herein, slag losses (e.g.,of an oxide-type) can be more easily avoided than in a conventionalmelt-metallurgical steel manufacturing process in which carbides,carbonitrides or nitrides precipitate during a heat treatment.

According to a further exemplary embodiment the desired particles, whichare the carbides, carbonitrides, and/or nitrides of the transitionmetal, are generated by thermal precipitation in a single- or multi-stepheat treatment subsequent to the deposition welding. This heat-treatmentprocess may be carried out, e.g., at a constant temperature, in aplurality of isothermal steps or at any varying temperatures, preferablywith peak temperatures respectively between approximately 500 and 1250°C.

According to a further exemplary embodiment at least one reshapingtreatment and at least one heat treatment are combined with one anotherin any sequence in order to generate the desired particles in thecoating by precipitation processes. According to a further exemplaryembodiment a brief solution annealing takes place beforehand at atemperature between 1000 and 1250° C. in order to thus dissolve in thematrix the larger particles formed during the solidification for thelater precipitation of the desired small particles.

According to a further exemplary embodiment a closing further step alsotakes place after the above-mentioned steps, in order, for example, toform in the coating a martensitic or bainitic microstructure havingdesired mechanical properties (e.g., hardness). Here the sizes and thedistribution of the precipitated particles no longer changesignificantly.

Furthermore the bearing component can also have at least one furthercoating, which is applied onto the first-mentioned coating using afurther deposition welding (cladding). In principle a plurality ofcorresponding coatings (multi-layer coatings) can be providedone-over-the-other. Here the further coating is applied in particularonto the first-mentioned coating in a similar manner, i.e., again by acorresponding deposition welding.

Finally a final other coating, which can serve, for example, to improvethe tribological properties, to increase the corrosion resistance,and/or to inhibit the conduction of electric current can be applied ontothe coating generated by the deposition welding in one layer or in aplurality of layers. Black oxidation, PVD (physical vapor deposition),CVD (chemical vapor deposition), or plasma spraying (e.g.,non-conductive aluminum oxide) can be mentioned here as examples.

Further advantages and advantageous embodiments are specified in thedescription, the drawings, and the claims. Here in particular thecombinations of features specified in the description and in thedrawings are purely exemplary, so that the features can also be presentindividually or combined in other ways.

In the following the disclosure shall be described in more detail usingexemplary embodiments depicted in the drawing. Here the exemplaryembodiments and the combinations shown in the exemplary embodiments arepurely exemplary and are not intended to define the scope of theinvention. This scope is defined solely by the pending claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic cross-sectional view of a rolling-element bearingaccording to the present disclosure.

DETAILED DESCRIPTION

In the following, identical or functionally equivalent elements aredesignated by the same reference numbers.

In FIG. 1 a rolling-element bearing 1 is illustrated that includes abearing inner ring 2 having a raceway 9 and a bearing outer ring 3having a raceway 10. Rolling elements 4 are disposed therebetween thatroll on the raceways 9, 10.

The bearing inner ring 2 includes a base body (core) 5 that forms thebearing inner ring 2 and a metallic coating (cladding) 6 applied ontothe base body 5, which metallic coating 6 forms the raceway for therolling elements 4. Here the coating 6 is applied onto the base body 5by deposition welding (cladding, e.g., laser cladding).

The base body 5 optionally may be manufactured from a non-alloy steel,for example, S235, S355, C22, or C35. In such embodiments of the presentteachings, the base body 5 can be manufactured relativelycost-effectively due to the selection of a less expensive material forthe core. The coating 6 itself includes an alloy steel, which enablesthe required hardness and rolling contact fatigue resistance to beachieved for the raceway 9.

According to one preferred exemplary embodiment the alloy of the coating6 comprises the through-hardened rolling-element-bearing steel 100Cr6 asthe base steel, and the transition metal zirconium in a concentration of2.0 wt. % as a further component. This comparatively high proportion ofthe transition metal zirconium can be made possible in the alloy sincethe coating 6 is applied onto the base body 5 by the deposition weldingprocess, wherein the alloy is formed “in situ” in the welding process.It is noted, for purposes of comparison, that such a high proportion ofthe transition metal can be achieved using known steel manufacturingtechniques only with considerable technical effort.

The bearing outer ring 3 also may be formed in an analogous manner; inparticular, the bearing outer ring 3 may include a base body 7 and acoating 8 that is applied in a similar manner onto the raceway of thebearing outer ring 3.

In summary a bearing component is provided that includes a base body anda coating, wherein the coating is distinguished by exhibiting aparticularly high hardness and rolling wear resistance. Here the coatingis formed on the base body “in situ” during a deposition weldingprocess. In comparison to conventional melt-metallurgical steelmanufacturing, with subsequent precipitation of carbides, carbonitrides,or nitrides, e.g., in the context of a heat treatment, using theinventive method, slag losses in particular can be more easily avoidedduring steel manufacturing.

Representative, non-limiting examples of the present invention weredescribed above in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove may be utilized separately or in conjunction with other featuresand teachings to provide improved bearing components having metallicbase bodies and an alloy-steel coating.

Moreover, combinations of features and steps disclosed in the abovedetailed description may not be necessary to practice the invention inthe broadest sense, and are instead taught merely to particularlydescribe representative examples of the invention. Furthermore, variousfeatures of the above-described representative examples, as well as thevarious independent and dependent claims below, may be combined in waysthat are not specifically and explicitly enumerated in order to provideadditional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

REFERENCE NUMBER LIST

-   -   1 Rolling-element bearing    -   2 Bearing inner ring    -   3 Bearing outer ring    -   4 Rolling element    -   5 Base body of the bearing inner ring    -   6 Coating of the bearing inner ring    -   7 Base body of the bearing outer ring    -   8 Coating of the bearing outer ring    -   9 Raceway of the bearing inner ring    -   10 Raceway of the bearing outer ring

What is claimed is:
 1. A bearing component, including: a metallic basebody constituting a core of the bearing component and being composed ofa non-alloy steel; and at least one alloy steel coating forming acladding that is fused to a raceway surface of the core; wherein: thenon-alloy steel has a composition (in wt %) of C: ≤0.4, Mn: ≤1.60, Ni:≤0.4, P: ≤0.05, S: ≤0.05, Si: ≤0.4, Cr: ≤0.4, Mo: ≤0.1, N: ≤0.009, theremainder being iron and unavoidable impurities; and the cladding has acomposition (in wt %) of C: 0.93-1.05, Si: 0.15-0.75, Mn: 0.25-1.20, P:≤0.025, S: ≤0.015, Cr: 1.35-2.05, Mo: ≤0.060, Al: ≤0.050, Cu: ≤0.30, anda total of 0.5-3 wt % of the at least one carbide-forming transitionmetal, which is selected from the group consisting of Nb, Ta, and Zr,the remainder being iron and unavoidable impurities.
 2. The bearingcomponent according to claim 1, wherein: the cladding has a thicknessthat is between 1-10% of a total thickness of the core and the cladding;the core and the cladding each contain at least 70 volume % martensiticand/or bainitic microstructure; the cladding contains between 1-10volume % of carbide-transition metal particles; the carbide-transitionmetal particles in the cladding have a number-weighted average particlesize of 1 micron or less; the at least one carbide-forming transitionmetal includes at least Nb; and the bearing component is a bearing ring.